I haven't been sick in 12 years. Yet, every year, I pay taxes to keep the public healthcare system running. Even though it's not something I use, undoubtedly, there are people who need it, and wouldn't be able to pay for it if it wasn't public.
About a month ago, I exhibited the symptoms of some kind of ventricular tachycardia (heart arrhythmia). As advised by a friend in medicine (in a different city), I tried to get myself booked for an ECG, to see what exactly was wrong. Without getting into the details, let's just say that even to this day, I haven't been able to get one.
I can definitely see why people don't want to pay, not just for services that they'll never use, but for services they'll probably be unable to use, even if they ever need to.
Procedures like ECGs arent performed at patient request, they're performed by specialists when a qualified physician determines a need for one and refers you to a specialist.
You can't get yourself an ECG not because they're unavailable, but simply because "Joe Random from city X says you need one" caries as much weight with Heart Specialists as "my cousin Bob says you should give me a new laptop" does with warrantee repairmen.
Like msbarnett says, you can't just roll into a clinic and say "I don't feel well and I'm scared and my cousin who's totally a doctor thinks this is what I should do! Also an MRI please!" Go see a doctor, and let them decide what diagnostic tests are appropriate, and you'll get them done.
The amount of inefficiency, conflicts of interest, hypocrisy, bureaucracy, and redundancy in the U.S. system beggars belief.